I am loosing over 50 percent of my young pigeons to a disease. All the adults are healthy... lay eggs and raise squabs with no problems. Young birds leave the nest and get weaned.. then independent... still no problems. But a couple months later some of these young birds will suddenly get ill and die. This has been happening for about one year now!!!!! The only symptoms are that the bird suddenly becomes lethargic and stops eating and drinking. Once I see a bird like that I know it will be dead the next day or in a few days time. The birds seem in perfect health... no problems with poops or breathing.. not fluffed up and not sleeping. They seem bright eyed and alert and good body and feather condition. Then they will just stop eating and quickly waste away and have no energy.. too weak to even fly.. then die. If one is sitting on the perch.. just me picking it up can made is die in my hands in seconds.. when only one or two days ago it was lively and fit.. flying about. This is very upsetting for me. I have only had 2 birds recover from this sickness.. both without any help from me. I must have lost over 30 youngsters to this disease. I have tried treating them with anti biotic for e coli infections.. and also isolating a sick bird and keeping it warm.. force feeding... etc.. but this had no effect. The coop has been cleaned out many times and its always very clean with a deep layer of dry sand on the bottom. They are fed 2 X a day in a special feeder so no seed get poop on it... and the water is changed 2 times a day and has apple cider vinegar in it several times a week. They get grit, mixed pigeon seed, chickens layer pellets... and are free range for several hours each afternoon. I have taken a few sick birds to the vet... but it just ended up costing me a great deal of money and the birds still died. I have introduced new adult birds from a friends loft a few months ago.. and these did not get sick. Any experienced pigeon fanciers have any advise about this? I have stopped all breeding again now as I can't stand loosing any more birds.. they are fancy breeds and pets.